This work is part of a project for evaluating catastrophic tank failures caused by impacts with a high-speed solid body. Previous studies on shock overpressure and drag events have provided analytical predictions, but they are not sufficient to explain ejection of liquid from the tank. This study focuses on the hydrodynamic behavior of the liquid after collision to explain subsequent ejection of liquid. The study is characterized by use of high-velocity projectiles and analysis of projectile dynamics in terms of energy loss to tank contents. New tests were performed at two projectile velocities (963 and 1255 m s(-1)) and over a range of viscosities (from 1 to 23.66 mPa s) of the target liquid. Based on data obtained from a high-speed video recorder, a phenomenological description is proposed for the evolution of intense pressure waves and cavitation in the target liquids.
a b s t r a c tSince the events of September 11, 2001, the possibility of an intentional act targeting the chemical process industry has become realistic. It is, therefore, a great concern to be able to predict the immediate consequences of such an act. This study is intended to improve our knowledge about the sequence of events that occurs when a high-speed bullet (41000 m s À1 ) penetrates a vessel filled with toxic liquid. We find that, prior to liquid ejection, several well-defined phases occur, including the phenomenon known as the ''hydraulic ram.'' This paper focuses on projectile-target interactions and explains how the decay of projectile velocity is related to the initial conditions of the target.
We have studied the sequence of events that occurs when a high-speed projectile (from 960 ms(-1) to 1480 ms(-1)) penetrates a vessel filled with toxic liquid. We find that prior to liquid ejection several well-defined phases occur, including the phenomenon known as the "hydraulic ram." Then a catastrophic tank failure leads to liquid ejection and fragmentation. This paper focuses on this phenomenon and explains how it can be related to the initial conditions of the target.
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AbstractAfter the detonation of an oxygen-deficient homogeneous high explosive, a phase of turbulent combustion, called afterburning, takes place at the interface between the rich detonation products and air. Its modelling is instrumental for the accurate prediction of the performance of these explosives. Because of the high temperature of detonation products, the chemical reactions are mixing-driven. Modelling afterburning thus relies on the precise description of the mixing process inside fireballs. This work presents a joint numerical and experimental study of a non-reacting reduced-scale set-up, which uses the compressed balloon analogy and does not involve the detonation of a high explosive. The set-up produces a flow similar to the one caused by a spherical detonation and allows focusing on the mixing process. The numerical work is composed of 2D and 3D LES simulations of the set-up. It is shown that grid independence can be reached by imposing perturbations at the edge of the fireball. The results compare well with the existing literature and give new insights on the mixing process inside fireballs. In particular, they highlight the fact that the mixing layer development follows an energetic scaling law but remains sensitive to the density ratio between the detonation products and air.
High-speed imaging optical techniques for shockwave and droplets atomization analysis," Abstract. Droplets atomization by shockwave can act as a consequence in domino effects on an industrial facility: aggression of a storage tank (projectile from previous event, for example) can cause leakage of hazardous material (toxic and flammable). As the accident goes on, a secondary event can cause blast generation, impacting the droplets and resulting in their atomization. Therefore, exchange surface increase impacts the evaporation rate. This can be an issue in case of dispersion of such a cloud. The experiments conducted in the lab generate a shockwave with an open-ended shock tube to break up liquid droplets. As the expected shockwave speed is about 400 m∕s (∼Mach 1.2), the interaction with falling drops is very short. High-speed imaging is performed at about 20,000 fps. The shockwave is measured using both overpressure sensors: particle image velocimetry and pure in line shadowgraphy. The size of fragmented droplets is optically measured by direct shadowgraphy simultaneously in different directions. In these experiments, secondary breakups of a droplet into an important number of smaller droplets from the shockwave-induced flow are shown. The results of the optical characterizations are discussed in terms of shape, velocity, and size.
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